NORTHGLENN, Colo. -- An arrest warrant has just been issued against a Northglenn mother on charges of felony child abuse and conspiracy.

Velta Asplin faces felony charges after her 4-year-old son, Kurt Green, suffered life-threatening injuries while in the care of her fiance, Michael Ochsner.

Ochsner took the boy to North Suburban Medical Center last Friday telling doctors the boy had fallen down a flight of stairs. The hospital staff said that the boy's injuries were not consistent with the fall, so they called police.

Investigators said Ochsner later confessed.

"He ultimately admitted he had struck the 4-year-old with a closed fist out of anger," said Northglenn police Cmdr. Steve Sanders.

Ochsner was booked on felony child abuse resulting in serious bodily injury.

The boy was airlifted to The Children's Hospital on Friday to go into emergency surgery. He has been upgraded to serious condition but remains in the hospital.